A particular case of a drive device as described in general terms above is a tracked drive device provided for driving cables, tubes or other elements with an essentially cylindrical cross-section in a longitudinal translation movement.
The U.S. Pat. No. 5,884,384 describes a method of placing, by blowing, one or more empty cables or tubes in a tube laid in the ground. The device used for this purpose comprises two endless chains, each carrying a plurality of drive pieces disposed successively on the chain, and depicted for example in U.S. Pat. No. 2,679,924, each of the said drive pieces being provided with a driving sole plate having a form adapted to the element or elements to be driven. A rectilinear length of each of the chains circulates in parallel, facing the corresponding length of the other chain, the element or elements to be driven being clamped between the driving sole plates of the drive pieces facing each other.
Since the driving sole plates mounted on the chains have a form and dimensions adapted to the element or elements to be driven, it is necessary to change the said sole plates or respectively to change the chain, at each change of form or dimension of the element to be placed.
Moreover, safety standards require that each of the two chains as well as the drive pieces and sole plates be housed in frames, casing or hoods, arranged so that it is impossible to accidentally slide therein a finger or any other part of the human body, so as to prevent any injury.
This latter requirement therefore makes it difficult to gain access to the chains in order to be able to remove them so as to exchange them for chains provided with drive pieces or respectively sole plates having a form and dimensions adapted to the next product to be placed.